Fall 2015 Cover Crop Grazing

With the general success of our first and second cover crop projects this spring we decided to try it again. Working with the advice of a retired sheep grazer we decided to plant a mix of sudan grass, forage radish, and forage brassica after our 2015 pea crop. The primary goal with this seed mix was to provide grazing for cattle.

This was a gravity-irrigated field so many of our decisions revolved around retaining irrigation ease. Around the middle of July, after the peas had been harvested, we brought our "row drill" in on the existing beds and seeded our cover crop. We then pulled a cultivator to eliminate a few remaining weeds (mostly nightshade) and redefine the corrugates. Once the crop was 8-10" tall we pulled the cultivator again to reduce some weed pressure (redroot pigweed) and clean the corrugates.

The "row drill" is a bit of farmer-engineered machinery originally created to plant peas on a 30" bed. It started off as a 13' grain drill but by remove some seed units and moving others closer together it is now able to plant 3 rows of seed on a 30" bed that are each 8" apart. This configuration puts all the seed on top of the bed so the corrugates are unobstructed. By operating as a drill rather than a row-crop planter it can handle many seed sizes and produce a thicker stand.

Somewhere around the end of August the sudan grass was 4' tall, growing rapidly, and heading into the boot stage. We decided that there was plenty of forage out there and it was time to bring in the cows. We had made previous arrangements with a local cattleman to put his herd on this field to give us the stock density to reduce this massive forest of grass.

The basic grazing setup was around 100 cows confined to a 2.5 acre paddock for 3 days then moved to the next section. As soon as the cows had moved we recorrugated that paddock and gave it one last irrigation before the season was over to promote some regrowth.



Here is what the plants looked like when the cows were moved off a section. If you look closely you can see some redroot pigweed hiding under the grass but it was grossly out-competed by the sudan grass and posed little concern.



Our grazing goal was to leave around half the vegetation in the field to allow the cover crop to regrow before winter. We may have removed a bit more than that but there was still plenty of green leaves to allow the plants to recover quickly.



Here is the regrowth on the first paddock after a quick irrigation and 10 days of growing time. Clearly these plants are as vigorous as ever and ready to provide more forage if needed.

By early October the cattle had grazed the entire 25 acre field once and it was time to send them down the road. The two main driving factors for this choice over regrazing the first part of the field were the need to perform fall tillage and the increasing risk of frost (and consequential prussic acid content in the sudan grass).



There was enough regrowth on the first paddocks to provide more grazing if the situation were different.



Even the places that were grazed a bit more heavily than intended were starting to regrow.



Notice the increasing dry residue on the ground as these pictures move across the field following the cattle movement. While the cows were grazing a section, the rest of the cover continued to grow and even go into reproduction. The straw on the ground is the sudan grass stalks that the cows were not interested in because of maturity.



Even though the cows did not eat the stalks they made a point to eat the green leaves off the stems before it was trampled too heavily. The sudan grass regrew from the crown of the plants rather than any remaining stem. If managed properly, I understand this quality can provide succulent forage for multiple grazing opportunities in a season.



As part of our residue management, we decided to shred the remaining stalk prior to doing any tillage. This field was to be planted to peppermint at the end of October and we didn't want any masses of straw to cause planting problems.